mm/Sub-mm Wave Compressive Sensing Imaging

电磁频谱的毫米波到太赫兹（mmw-THz，30 GHz-3 THz）区域的成像为我们周围世界的调查和感知提供了新的维度。 毫米波成像已被广泛用于机场的威胁探测和射电天文学的科学发现，以识别数千光年外气体云中的粒子。 太赫兹成像显示了一种研究生物组织的新方法，特别是在肿瘤筛查中。虽然其科学和社会效益是巨大的，但毫米波太赫兹成像领域仍处于起步阶段。一个特别严峻的挑战是，在电路板上集成大量的mmw-THz传感器是不切实际的，因为每个“像素”的大小必须至少与波长成比例。不幸的是，使用单个传感器或少量传感器使得当前的mmw-THz成像系统太慢。在这项工作中，我们将研究一种新的毫米波太赫兹成像方法，使用压缩传感和数字毫米波太赫兹可配置的透镜，以提供高达32倍的分辨率或速度的改善。压缩传感可以减少重建图像所需的信息，从而使光学成像器，需要减少70-80%的测量。这种减少的关键是使用伪随机空间调制器或掩模。 然而，在mmw-THz频率中，由于每个调制器“像素”的大小需要至少与波长成比例，因此不存在这样的空间调制器。因此，mmw-THz无法利用这些新方法。在这个项目中，我们将通过结合几个研究领域来研究mmw-THz成像的变革性解决方案。首先，光子诱导的动态空间调制器将用于毫米波-太赫兹频率。其次，先进的压缩传感算法将从减少的测量数量重建高保真图像。第三，多传感器阵列将加速图像采集，并且信号处理算法将解释所有传感器采集的图像的共享结构。由此产生的系统有可能提供每秒50-100帧的速度和大大提高的信噪比。

Imaging in the millimeter-wave to terahertz (mmw-THz, 30GHz-3THz) region of the electromagnetic spectrum provides a new dimension to the investigation and perception of the world around us. Millimeter wave imaging has been extensively used for threat detection at airports and for scientific discovery in radio astronomy to identify particles in gas clouds thousands of light years away. Terahertz imaging has shown a new means to investigate biological tissues, in particular in tumor screening. While the scientific and societal benefits are enormous, the field of mmw-THz imaging is still in its infancy. A particularly acute challenge is that it is impractical to integrate a large number of mmw-THz sensors on a circuit board, because the size of each "pixel" must be at least proportional to the wavelength. Unfortunately, using a single sensor or small number of sensors renders current mmw-THz imaging systems far too slow. In this work we will investigate a new method for mmw-THz imaging that uses compressive sensing and a digital mmw-THz configurable lens to provide up to a 32x improvement in resolution or speed.Compressive sensing allows a reduction in the information needed to reconstruct an image, thus enabling optical imagers that require 70-80% fewer measurements. Key to this reduction is the use of pseudorandom spatial modulators, or masks. In the mmw-THz frequencies, however, such spatial modulators do not exist, due to the size of each modulator "pixel" needing to be at least proportional to the wavelength. Consequently, mmw-THz has not been able to leverage these new approaches. In this project, we will investigate a transformative solution to mmw-THz imaging by combining several research areas. First, photon induced dynamic spatial modulators will be used for mmw-THz frequencies. Second, advanced compressive sensing algorithms will reconstruct high fidelity images from a reduced number of measurements. Third, multi-sensor arrays will accelerate the image acquisition, and signal processing algorithms will account for the shared structure of the image being acquired by all the sensors. The resulting system has the potential to provide speeds of 50-100 frames per second and greatly increased signal-to-noise ratio.